1. Field of the Invention
The present invention relates to novel compounds useful as intermediates for antibacterial agents.
2. Brief Description of the Prior Art
4-Substituted-azetidin-2-ones hitherto known as important intermediates for carbapenem antibacterial agents, as are shown in, e.g., J. Am. Chem. Soc., vol. 103, page 2406 (1981), Tetrahedron Lett., page 3009 (1983), J. Org. Chem., vol. 45, page 1135 (1980), J. Org. Chem., vol. 45, page 1143 (1980), etc. In the carbapenem skeleton, the following two isomers are present: ##STR2##
Of these, carbapenem derivatives having the .beta.-configuration exhibit much higher antibacterial activity and carbapenem antibacterial agents including thienamycin which are presently under development all have this configuration. Therefore, compounds having a configuration capable of leading to carbapenems of this .beta.-configuration are desired as intermediates; from a viewpoint of synthesis, however, it was difficult to obtain only 4-substituted-azetidin-2-one derivatives having a specific configuration in a simple manner and high yield. The present inventors have found that when the compounds of the present invention are used, 4-substituted-azetidin-2-one derivatives having a specific configuration can easily be obtained, and have accomplished the present invention.